WScriptShell_Case_Anomaly

rule WScriptShell_Case_Anomaly {
   meta:
      description = "Detects obfuscated wscript.shell commands"
      license = "Detection Rule License 1.1 https://github.com/Neo23x0/signature-base/blob/master/LICENSE"
      author = "Florian Roth (Nextron Systems)"
      reference = "Internal Research"
      date = "2017-09-11"
      modified = "2022-06-09"
      score = 60
      id = "d69d932d-1e39-5259-9200-f0227754f49c"
   strings:
      // first detect powershell keyword case insensitive
      $s1 = "WScript.Shell\").Run" nocase ascii wide
      // define the normal cases
      $sn1 = "WScript.Shell\").Run" ascii wide
      $sn2 = "wscript.shell\").run" ascii wide
      $sn3 = "WSCRIPT.SHELL\").RUN" ascii wide
      $sn4 = "Wscript.Shell\").Run" ascii wide
      $sn5 = "WScript.shell\").Run" ascii wide
   condition:
      filesize < 3000KB and
      #s1 > #sn1 + #sn2 + #sn3 + #sn4 + #sn5
}